It is often helpful to know how much a winch or similar device is lifting or pulling. To find this, theoretically, the torque applied by the winch is divided by the distance between the center axis of the winch or similar device and the location where the rope exits the winch or similar device. The equation for this is F=T/X, where F is the weight of the load (or line pull), T the output torque and X is the distance from the center axis of the winch or similar device perpendicular to the point where the rope exits the winch or similar device. In actuality, this calculation is more complicated. The rope rarely winds perfectly onto the drum. Much of the time the line is allowed to wind onto the drum or similar device in a random fashion, creating peaks and valleys for the line to rise and fall into as it changes layers. This means that the X mentioned above is constantly changing.